Our overall objective is to identify, isolate, purify and characterize tumor-associated and organ-associated antigens of human colonic tumors. The model developed as a source of such antigens is xenografted human colonic carcinomas, utilizing both hamsters and nude (athymic) mice, as well as cell cultures derived therefrom. Since these experiences with human tumor systems have been found to produce a number of human tumor-associated and organ-associated antigens (CEA, CSA's and CSAp), these systems will be explored further for the presence of other antigens which might be of additional immunodiagnostic or immunotherapeutic importance. However, the major emphasis of this project is the further elucidation of the immunology, immunochemistry, and immunocytochemistry of two new antigen systems described by us in our previous work, colon-specific antigens (CSA's) and colon-specific antigen-protein (CSAp). The latter antigen (CSAp) has been found to be quantitatively increased in rapidly proliferating gastrointestinal tissues, especially colonic polyps and carcinomas, and has also been found to circulate in the blood of patients with colonic cancer. Hence, our immediate concern is the further isolation, purification, and chemical characterization of CSAp. We are also interested in the growth behavior and phenotypic expression of colonic carcinomas and polyps in hamsters and nude mice.